1 /*
2 * Copyright (c) 2021 Paul B Mahol
3 *
4 * This file is part of FFmpeg.
5 *
6 * FFmpeg is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
10 *
11 * FFmpeg is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with FFmpeg; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20
21 /**
22 * @file
23 * Change the PTS/DTS timestamps.
24 */
25
26 #include "libavutil/opt.h"
27 #include "libavutil/eval.h"
28
29 #include "avcodec.h"
30 #include "bsf.h"
31 #include "bsf_internal.h"
32
33 static const char *const var_names[] = {
34 "N", ///< frame number (starting at zero)
35 "TS",
36 "POS", ///< original position in the file of the frame
37 "PREV_INPTS", ///< previous input PTS
38 "PREV_INDTS", ///< previous input DTS
39 "PREV_OUTPTS", ///< previous output PTS
40 "PREV_OUTDTS", ///< previous output DTS
41 "PTS", ///< original PTS in the file of the frame
42 "DTS", ///< original DTS in the file of the frame
43 "STARTPTS", ///< PTS at start of movie
44 "STARTDTS", ///< DTS at start of movie
45 "TB", ///< timebase of the stream
46 "SR", ///< sample rate of the stream
47 NULL
48 };
49
50 enum var_name {
51 VAR_N,
52 VAR_TS,
53 VAR_POS,
54 VAR_PREV_INPTS,
55 VAR_PREV_INDTS,
56 VAR_PREV_OUTPTS,
57 VAR_PREV_OUTDTS,
58 VAR_PTS,
59 VAR_DTS,
60 VAR_STARTPTS,
61 VAR_STARTDTS,
62 VAR_TB,
63 VAR_SR,
64 VAR_VARS_NB
65 };
66
67 typedef struct SetTSContext {
68 const AVClass *class;
69
70 char *ts_str;
71 char *pts_str;
72 char *dts_str;
73
74 int64_t frame_number;
75
76 int64_t start_pts;
77 int64_t start_dts;
78 int64_t prev_inpts;
79 int64_t prev_indts;
80 int64_t prev_outpts;
81 int64_t prev_outdts;
82
83 double var_values[VAR_VARS_NB];
84
85 AVExpr *ts_expr;
86 AVExpr *pts_expr;
87 AVExpr *dts_expr;
88 } SetTSContext;
89
setts_init(AVBSFContext * ctx)90 static int setts_init(AVBSFContext *ctx)
91 {
92 SetTSContext *s = ctx->priv_data;
93 int ret;
94
95 if ((ret = av_expr_parse(&s->ts_expr, s->ts_str,
96 var_names, NULL, NULL, NULL, NULL, 0, ctx)) < 0) {
97 av_log(ctx, AV_LOG_ERROR, "Error while parsing ts expression '%s'\n", s->ts_str);
98 return ret;
99 }
100
101 if (s->pts_str) {
102 if ((ret = av_expr_parse(&s->pts_expr, s->pts_str,
103 var_names, NULL, NULL, NULL, NULL, 0, ctx)) < 0) {
104 av_log(ctx, AV_LOG_ERROR, "Error while parsing pts expression '%s'\n", s->pts_str);
105 return ret;
106 }
107 }
108
109 if (s->dts_str) {
110 if ((ret = av_expr_parse(&s->dts_expr, s->dts_str,
111 var_names, NULL, NULL, NULL, NULL, 0, ctx)) < 0) {
112 av_log(ctx, AV_LOG_ERROR, "Error while parsing dts expression '%s'\n", s->dts_str);
113 return ret;
114 }
115 }
116
117 s->frame_number= 0;
118 s->start_pts = AV_NOPTS_VALUE;
119 s->start_dts = AV_NOPTS_VALUE;
120 s->prev_inpts = AV_NOPTS_VALUE;
121 s->prev_indts = AV_NOPTS_VALUE;
122 s->prev_outpts = AV_NOPTS_VALUE;
123 s->prev_outdts = AV_NOPTS_VALUE;
124
125 return 0;
126 }
127
setts_filter(AVBSFContext * ctx,AVPacket * pkt)128 static int setts_filter(AVBSFContext *ctx, AVPacket *pkt)
129 {
130 SetTSContext *s = ctx->priv_data;
131 int64_t new_ts, new_pts, new_dts;
132 int ret;
133
134 ret = ff_bsf_get_packet_ref(ctx, pkt);
135 if (ret < 0)
136 return ret;
137
138 if (s->start_pts == AV_NOPTS_VALUE)
139 s->start_pts = pkt->pts;
140
141 if (s->start_dts == AV_NOPTS_VALUE)
142 s->start_dts = pkt->dts;
143
144 s->var_values[VAR_N] = s->frame_number++;
145 s->var_values[VAR_TS] = pkt->dts;
146 s->var_values[VAR_POS] = pkt->pos;
147 s->var_values[VAR_PTS] = pkt->pts;
148 s->var_values[VAR_DTS] = pkt->dts;
149 s->var_values[VAR_PREV_INPTS] = s->prev_inpts;
150 s->var_values[VAR_PREV_INDTS] = s->prev_indts;
151 s->var_values[VAR_PREV_OUTPTS] = s->prev_outpts;
152 s->var_values[VAR_PREV_OUTDTS] = s->prev_outdts;
153 s->var_values[VAR_STARTPTS] = s->start_pts;
154 s->var_values[VAR_STARTDTS] = s->start_dts;
155 s->var_values[VAR_TB] = ctx->time_base_out.den ? av_q2d(ctx->time_base_out) : 0;
156 s->var_values[VAR_SR] = ctx->par_in->sample_rate;
157
158 new_ts = llrint(av_expr_eval(s->ts_expr, s->var_values, NULL));
159
160 if (s->pts_str) {
161 s->var_values[VAR_TS] = pkt->pts;
162 new_pts = llrint(av_expr_eval(s->pts_expr, s->var_values, NULL));
163 } else {
164 new_pts = new_ts;
165 }
166
167 if (s->dts_str) {
168 s->var_values[VAR_TS] = pkt->dts;
169 new_dts = llrint(av_expr_eval(s->dts_expr, s->var_values, NULL));
170 } else {
171 new_dts = new_ts;
172 }
173
174 s->var_values[VAR_PREV_INPTS] = pkt->pts;
175 s->var_values[VAR_PREV_INDTS] = pkt->dts;
176 s->var_values[VAR_PREV_OUTPTS] = new_pts;
177 s->var_values[VAR_PREV_OUTDTS] = new_dts;
178
179 pkt->pts = new_pts;
180 pkt->dts = new_dts;
181
182 return ret;
183 }
184
setts_close(AVBSFContext * bsf)185 static void setts_close(AVBSFContext *bsf)
186 {
187 SetTSContext *s = bsf->priv_data;
188
189 av_expr_free(s->ts_expr);
190 s->ts_expr = NULL;
191 av_expr_free(s->pts_expr);
192 s->pts_expr = NULL;
193 av_expr_free(s->dts_expr);
194 s->dts_expr = NULL;
195 }
196
197 #define OFFSET(x) offsetof(SetTSContext, x)
198 #define FLAGS (AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_AUDIO_PARAM|AV_OPT_FLAG_SUBTITLE_PARAM|AV_OPT_FLAG_BSF_PARAM)
199
200 static const AVOption options[] = {
201 { "ts", "set expression for packet PTS and DTS", OFFSET(ts_str), AV_OPT_TYPE_STRING, {.str="TS"}, 0, 0, FLAGS },
202 { "pts", "set expression for packet PTS", OFFSET(pts_str), AV_OPT_TYPE_STRING, {.str=NULL}, 0, 0, FLAGS },
203 { "dts", "set expression for packet DTS", OFFSET(dts_str), AV_OPT_TYPE_STRING, {.str=NULL}, 0, 0, FLAGS },
204 { NULL },
205 };
206
207 static const AVClass setts_class = {
208 .class_name = "setts_bsf",
209 .item_name = av_default_item_name,
210 .option = options,
211 .version = LIBAVUTIL_VERSION_INT,
212 };
213
214 const AVBitStreamFilter ff_setts_bsf = {
215 .name = "setts",
216 .priv_data_size = sizeof(SetTSContext),
217 .priv_class = &setts_class,
218 .init = setts_init,
219 .close = setts_close,
220 .filter = setts_filter,
221 };
222